Lecture22_EAS1600_Fall08

Lecture22_EAS1600_Fall08 - EAS 1600 Introduction to...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: EAS 1600 Introduction to Environmental Sciences ____________________________ Lecture 22 Intro to the Carbon Cycle, Today we will begun to discuss the factors that control the cycling of carbon both inorganic and organic. We will also introduce box models and biogeochemical cycles. Inorganic carbon in the Earths environment is primarily composed of CaCO 3(s) , CO 2(g) , H 2 CO 3(aq) , HCO 3- (aq) , and CO 3-2 (aq) CaCO 3 is primarily limestone in both continental and oceanic sediments. CO 2 is a greenhouse gas in the atmosphere H 2 CO 3(aq) , HCO 3- (aq) , and CO 3-2 (aq) are found in the ocean as well in fresh water. The concentration of CO 2 in the atmosphere is controlled by several factors including ocean uptake, photosynthesis, and fossil fuel burning. The other forms of inorganic carbon are largely controlled by pH controlled equilibria Oceanic Inorganic Carbon In typical ocean water: [HCO 3- ] = 5 x 10-4 mole/liter [H 2 CO 3 ] = 1.1 x 10-5 mole/liter Remember that for H 2 CO 3 K a = 4.3 x 10-7 [ ] 7 4.3x10 3 CO 2 H 3 HCO H = + [H + ] = 9.5 x 10-9 mole/liter pH = 8.0 The ocean pH of ~ 8 (slightly basic) is due to the bicarbonate dissolved in the ocean. The bicarbonate is much higher than dissolved carbonic acid so it must be formed from other source. i.e. since carbonic acid is a weak acid it will not dissolve to make more bicarbonate than carbonic acid. Where does the HCO 3- come from? CaCO 3 (s) + H 2 CO 3 (aq) 2HCO 3- (aq) + Ca +2 (aq) Limestone rock is weathered (dissolved) by carbonic acid in rain water. This produces bicarbonate in the runoff water that will eventually reach and collect in the ocean. Thus rock weathering (enhanced by acidic rain) produces bicarbonate in the ocean. The bicarbonate effectively sets and buffers the pH of the ocean. iogeochemical cycles are the chemical transformations that convert elements between their organic and inorganic forms. Together the two processes or reactions below represent a biogeochemical cycle a cycle with no net chemical change: Photosynthesis: CO 2 + H 2 O + h CH 2 O + O 2 + Respiration: CH 2 O + O 2 CO 2 + H 2 O + Energy Net: h Energy h = light from the sun That is: No net chemical change Remember Combustion CH 4 + O 2 CO 2 + H 2 O + Energy he Terms of Biogeochemical Cycles Biogeochemists often describe biogeochemical cycles using a so called box model approach....
View Full Document

Page1 / 26

Lecture22_EAS1600_Fall08 - EAS 1600 Introduction to...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online